xref: /openbmc/linux/arch/s390/kernel/machine_kexec.c (revision 3eeb0778)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright IBM Corp. 2005, 2011
4  *
5  * Author(s): Rolf Adelsberger,
6  *	      Michael Holzheu <holzheu@linux.vnet.ibm.com>
7  */
8 
9 #include <linux/device.h>
10 #include <linux/mm.h>
11 #include <linux/kexec.h>
12 #include <linux/delay.h>
13 #include <linux/reboot.h>
14 #include <linux/ftrace.h>
15 #include <linux/debug_locks.h>
16 #include <asm/pfault.h>
17 #include <asm/cio.h>
18 #include <asm/setup.h>
19 #include <asm/smp.h>
20 #include <asm/ipl.h>
21 #include <asm/diag.h>
22 #include <asm/elf.h>
23 #include <asm/asm-offsets.h>
24 #include <asm/cacheflush.h>
25 #include <asm/abs_lowcore.h>
26 #include <asm/os_info.h>
27 #include <asm/set_memory.h>
28 #include <asm/stacktrace.h>
29 #include <asm/switch_to.h>
30 #include <asm/nmi.h>
31 #include <asm/sclp.h>
32 
33 typedef void (*relocate_kernel_t)(unsigned long, unsigned long, unsigned long);
34 typedef int (*purgatory_t)(int);
35 
36 extern const unsigned char relocate_kernel[];
37 extern const unsigned long long relocate_kernel_len;
38 
39 #ifdef CONFIG_CRASH_DUMP
40 
41 /*
42  * Reset the system, copy boot CPU registers to absolute zero,
43  * and jump to the kdump image
44  */
__do_machine_kdump(void * data)45 static void __do_machine_kdump(void *data)
46 {
47 	struct kimage *image = data;
48 	purgatory_t purgatory;
49 	unsigned long prefix;
50 
51 	purgatory = (purgatory_t)image->start;
52 
53 	/* store_status() saved the prefix register to lowcore */
54 	prefix = (unsigned long) S390_lowcore.prefixreg_save_area;
55 
56 	/* Now do the reset  */
57 	s390_reset_system();
58 
59 	/*
60 	 * Copy dump CPU store status info to absolute zero.
61 	 * This need to be done *after* s390_reset_system set the
62 	 * prefix register of this CPU to zero
63 	 */
64 	memcpy(absolute_pointer(__LC_FPREGS_SAVE_AREA),
65 	       phys_to_virt(prefix + __LC_FPREGS_SAVE_AREA), 512);
66 
67 	call_nodat(1, int, purgatory, int, 1);
68 
69 	/* Die if kdump returns */
70 	disabled_wait();
71 }
72 
73 /*
74  * Start kdump: create a LGR log entry, store status of all CPUs and
75  * branch to __do_machine_kdump.
76  */
__machine_kdump(void * image)77 static noinline void __machine_kdump(void *image)
78 {
79 	struct mcesa *mcesa;
80 	union ctlreg2 cr2_old, cr2_new;
81 	int this_cpu, cpu;
82 
83 	lgr_info_log();
84 	/* Get status of the other CPUs */
85 	this_cpu = smp_find_processor_id(stap());
86 	for_each_online_cpu(cpu) {
87 		if (cpu == this_cpu)
88 			continue;
89 		if (smp_store_status(cpu))
90 			continue;
91 	}
92 	/* Store status of the boot CPU */
93 	mcesa = __va(S390_lowcore.mcesad & MCESA_ORIGIN_MASK);
94 	if (MACHINE_HAS_VX)
95 		save_vx_regs((__vector128 *) mcesa->vector_save_area);
96 	if (MACHINE_HAS_GS) {
97 		__ctl_store(cr2_old.val, 2, 2);
98 		cr2_new = cr2_old;
99 		cr2_new.gse = 1;
100 		__ctl_load(cr2_new.val, 2, 2);
101 		save_gs_cb((struct gs_cb *) mcesa->guarded_storage_save_area);
102 		__ctl_load(cr2_old.val, 2, 2);
103 	}
104 	/*
105 	 * To create a good backchain for this CPU in the dump store_status
106 	 * is passed the address of a function. The address is saved into
107 	 * the PSW save area of the boot CPU and the function is invoked as
108 	 * a tail call of store_status. The backchain in the dump will look
109 	 * like this:
110 	 *   restart_int_handler ->  __machine_kexec -> __do_machine_kdump
111 	 * The call to store_status() will not return.
112 	 */
113 	store_status(__do_machine_kdump, image);
114 }
115 
116 #endif /* CONFIG_CRASH_DUMP */
117 
118 /*
119  * Check if kdump checksums are valid: We call purgatory with parameter "0"
120  */
kdump_csum_valid(struct kimage * image)121 static bool kdump_csum_valid(struct kimage *image)
122 {
123 #ifdef CONFIG_CRASH_DUMP
124 	purgatory_t purgatory = (purgatory_t)image->start;
125 	int rc;
126 
127 	rc = call_nodat(1, int, purgatory, int, 0);
128 	return rc == 0;
129 #else
130 	return false;
131 #endif
132 }
133 
134 #ifdef CONFIG_CRASH_DUMP
135 
crash_free_reserved_phys_range(unsigned long begin,unsigned long end)136 void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
137 {
138 	unsigned long addr, size;
139 
140 	for (addr = begin; addr < end; addr += PAGE_SIZE)
141 		free_reserved_page(pfn_to_page(addr >> PAGE_SHIFT));
142 	size = begin - crashk_res.start;
143 	if (size)
144 		os_info_crashkernel_add(crashk_res.start, size);
145 	else
146 		os_info_crashkernel_add(0, 0);
147 }
148 
crash_protect_pages(int protect)149 static void crash_protect_pages(int protect)
150 {
151 	unsigned long size;
152 
153 	if (!crashk_res.end)
154 		return;
155 	size = resource_size(&crashk_res);
156 	if (protect)
157 		set_memory_ro(crashk_res.start, size >> PAGE_SHIFT);
158 	else
159 		set_memory_rw(crashk_res.start, size >> PAGE_SHIFT);
160 }
161 
arch_kexec_protect_crashkres(void)162 void arch_kexec_protect_crashkres(void)
163 {
164 	crash_protect_pages(1);
165 }
166 
arch_kexec_unprotect_crashkres(void)167 void arch_kexec_unprotect_crashkres(void)
168 {
169 	crash_protect_pages(0);
170 }
171 
172 #endif
173 
174 /*
175  * Give back memory to hypervisor before new kdump is loaded
176  */
machine_kexec_prepare_kdump(void)177 static int machine_kexec_prepare_kdump(void)
178 {
179 #ifdef CONFIG_CRASH_DUMP
180 	if (MACHINE_IS_VM)
181 		diag10_range(PFN_DOWN(crashk_res.start),
182 			     PFN_DOWN(crashk_res.end - crashk_res.start + 1));
183 	return 0;
184 #else
185 	return -EINVAL;
186 #endif
187 }
188 
machine_kexec_prepare(struct kimage * image)189 int machine_kexec_prepare(struct kimage *image)
190 {
191 	void *reboot_code_buffer;
192 
193 	if (image->type == KEXEC_TYPE_CRASH)
194 		return machine_kexec_prepare_kdump();
195 
196 	/* We don't support anything but the default image type for now. */
197 	if (image->type != KEXEC_TYPE_DEFAULT)
198 		return -EINVAL;
199 
200 	/* Get the destination where the assembler code should be copied to.*/
201 	reboot_code_buffer = page_to_virt(image->control_code_page);
202 
203 	/* Then copy it */
204 	memcpy(reboot_code_buffer, relocate_kernel, relocate_kernel_len);
205 	return 0;
206 }
207 
machine_kexec_cleanup(struct kimage * image)208 void machine_kexec_cleanup(struct kimage *image)
209 {
210 }
211 
arch_crash_save_vmcoreinfo(void)212 void arch_crash_save_vmcoreinfo(void)
213 {
214 	struct lowcore *abs_lc;
215 
216 	VMCOREINFO_SYMBOL(lowcore_ptr);
217 	VMCOREINFO_SYMBOL(high_memory);
218 	VMCOREINFO_LENGTH(lowcore_ptr, NR_CPUS);
219 	vmcoreinfo_append_str("SAMODE31=%lx\n", (unsigned long)__samode31);
220 	vmcoreinfo_append_str("EAMODE31=%lx\n", (unsigned long)__eamode31);
221 	vmcoreinfo_append_str("KERNELOFFSET=%lx\n", kaslr_offset());
222 	abs_lc = get_abs_lowcore();
223 	abs_lc->vmcore_info = paddr_vmcoreinfo_note();
224 	put_abs_lowcore(abs_lc);
225 }
226 
machine_shutdown(void)227 void machine_shutdown(void)
228 {
229 }
230 
machine_crash_shutdown(struct pt_regs * regs)231 void machine_crash_shutdown(struct pt_regs *regs)
232 {
233 	set_os_info_reipl_block();
234 }
235 
236 /*
237  * Do normal kexec
238  */
__do_machine_kexec(void * data)239 static void __do_machine_kexec(void *data)
240 {
241 	unsigned long data_mover, entry, diag308_subcode;
242 	struct kimage *image = data;
243 
244 	data_mover = page_to_phys(image->control_code_page);
245 	entry = virt_to_phys(&image->head);
246 	diag308_subcode = DIAG308_CLEAR_RESET;
247 	if (sclp.has_iplcc)
248 		diag308_subcode |= DIAG308_FLAG_EI;
249 	s390_reset_system();
250 
251 	call_nodat(3, void, (relocate_kernel_t)data_mover,
252 		   unsigned long, entry,
253 		   unsigned long, image->start,
254 		   unsigned long, diag308_subcode);
255 
256 	/* Die if kexec returns */
257 	disabled_wait();
258 }
259 
260 /*
261  * Reset system and call either kdump or normal kexec
262  */
__machine_kexec(void * data)263 static void __machine_kexec(void *data)
264 {
265 	pfault_fini();
266 	tracing_off();
267 	debug_locks_off();
268 #ifdef CONFIG_CRASH_DUMP
269 	if (((struct kimage *) data)->type == KEXEC_TYPE_CRASH)
270 		__machine_kdump(data);
271 #endif
272 	__do_machine_kexec(data);
273 }
274 
275 /*
276  * Do either kdump or normal kexec. In case of kdump we first ask
277  * purgatory, if kdump checksums are valid.
278  */
machine_kexec(struct kimage * image)279 void machine_kexec(struct kimage *image)
280 {
281 	if (image->type == KEXEC_TYPE_CRASH && !kdump_csum_valid(image))
282 		return;
283 	tracer_disable();
284 	smp_send_stop();
285 	smp_call_ipl_cpu(__machine_kexec, image);
286 }
287